The present invention relates to a new and improved construction of a tensioning- and friction welding apparatus for a band formed of thermoplastic material which is wrapped about an article, typically boxes, crates, packages and the like, comprising a welding-clamping jaw driven to-and-fro relative to a counter-clamping jaw by means of an inclined drive lever or the like, wherein the jaws engage with the ends of the band clamped therebetween which are also engaged by a return movement-blocking device, tension such band ends and after reaching a predetermined band tension weld the band ends to one another.
An apparatus of this general construction has become known to the art from German patent publication No. 2,521,474. This prior art apparatus is manifested by its particular simplicity in that, especially for tensioning and welding of the band ends always the same very simply constructed drive moves a single clamping jaw in the same manner back and forth. This state-of-the-art apparatus possesses a pair of blocking-clamping jaws which, during band tensioning, prevent return movement of the band. Both during tensioning as well as especially also during welding teeth of the different clamping jaws engage into the plastic bands, in order to thereby produce the requisite entrainment forces or holding forces between the clamping jaws and the plastic bands bearing thereagainst. Hence, it can happen that considerable effort is needed, following completion of the welding operation, to remove the clamping jaws, which are wedged against the band ends, from the latter without, as such is the case with other heretofore known equipment, having to spreadably arrange the entire clamping jaw-support together with the clamping jaws.